Concrete construction and more particularly the field of concrete construction form work and the apparatus employed for assembling such form work into functional units is the field of the subject invention. Specifically, this invention relates to anchoring apparatus for tying form work panels together by means of elongated ties. Particularly, the invention relates to the fastening devices or anchoring apparatus attachable to the ties to retain the panels against relative movement while the concrete is poured and setting up.
In the construction of concrete forms from panels maintained in spaced opposed relationship the prior art devices have proposed and utilized various constructions with differing degrees of success. Such devices have generally comprised a rod extending between and through both such panels with varying forms of wedging or locking devices provided to grip the ends of the tie and thus prevent outward movement of the form panels. Devices of this nature generally employ in conjunction with the forms, spacers to prevent inward movement of the forms. The rod end fastening devices are attached to walers on the form panels. The rod end fastening devices generally have taken the form of loops through which hooks are inserted, nuts treaded onto the end of a treaded tie, or a hot-upset "button" end similar to the head of a nail or bolt. One significant disadvantage that all such apparatus have suffered from, has been the difficulty of removal of the fastening device after the concrete structure has been poured and set. Expansion of the concrete during such setting greatly increases the outwardly exerted pressure against the form panels and thus against the tie rod and fastening devices to create this problem. Accordingly, it has required great force to release these prior art devices in order to remove the form panels. In removing the fastening devices the difficulty has resided principally in the inability of such devices to release the longitudinal stresses on the rod quickly upon the initiation of the releasing action. Another disadvantage suffered by structures using threaded ties and nuts or ties with enlarged headed ends, has been their inability to compensate for misalignment between the tie and the clamping structure on the form panel. Generally, this misalignment in prior art devices has been manifested by angular displacement of the tie from a line normal to the form panel. This misalignment has generally resulted in the imposition of longitudinal stress upon one corner or a very small portion of the tie end anchoring structure. Such a condition both increases the difficulty in releasing the clamp but also imposes severe bending stresses on the tie, leading to the potential for failure of the tie.
Considering the above mentioned disadvantages of the prior art devices an object of the present invention is to provide a concrete form tying apparatus in the form of an anchoring or clamping apparatus which may be quickly and easily installed to clamp form panels into place and may quickly and easily be removed to release such panels even when such panels are under great pressure from the concrete structure formed therein.
It is another object of this invention to provide a concrete form panel tying apparatus and specifically the anchoring apparatus for such a tie which simply and effectively compensates for some amount of misalignment between the tie and form panel, avoiding the imposition of excessive loading or bending of the form holding tie.